The present invention relates to a system for air flow cooling of electrical equipment chassis, and more particularly to a system that allows for different air flow volumes for separate thermal zones of a chassis.
In electronic systems, components such as circuit boards are typically housed in chassis or enclosures. It is common for the circuit boards to be arranged vertically side-by-side, and to plug into a backplane. It is also common to have a mid-located backplane with a set of circuit cards that plug into the backplane from the rear. In the past, this set of rear cards tended to comprise mostly passive components. However, the rear set of cards is now including more and more active components.
Typically, the circuit boards produce excess heat that must be removed from the chassis. This is commonly done using a fan pack for forced air ventilation placed at the top of the enclosure that draws air through openings at the bottom of the enclosure and past the circuit cards. Typically, all areas within the enclosure are in air-flow communication with each other, and the minimum required air flow through the chassis is governed by the area with the highest cooling requirements.
A problem with this common approach to cooling a chassis occurs when efficient air flow through the different areas, or zones, within the chassis is desired, and the different zones have different cooling requirements. For example, in the arrangement described above with a mid-located backplane, it is possible that the circuit cards located in front of the backplane have a much higher cooling requirement than the circuit cards located to the rear of the backplane. With all areas within the chassis communicating, it may be difficult to achieve efficient air flow rates in different chassis zones.
Accordingly, it is an object of the present invention to provide a system for air cooling a chassis wherein different zones within the chassis are efficiently cooled.
The present invention is a system for cooling an electrical chassis, in which, in a preferred embodiment, two separate zones are formed within the chassis through the use of horizontal separators forming an internal floor and a ceiling, and a backplane, acting as a vertical separator, spanning from floor to ceiling. The upper horizontal separator has openings allowing air flow. The lower horizontal separator may have openings, or may be solid, with the chassis side, front and rear panels having perforations or openings directly above the lower horizontal separator to allow air flow. An exhaust fan pack is placed above the ceiling separator and draws air through both zones. Air flow volume through the zones is controlled separately through the use of separate intake filters that may have different filter densities and sizes, and appropriate fan pack size.